A great achievement even for a game which is relatively simplistic like a MOBA. Still waiting for AI to become competitive in Starcraft which i think is a much greater challenge.
You could basically get an AI to win every single time with a handful of zerglings in a few minutes this way.
You could train an AI for 1 billion years a day to play pong or you could hardcode it to never miss the ball.
I think a smart player could know the player was going Zerg, and wall in.. and make some decisions that make the micro of Zerg less useful.
I'm not aware of any public api or hooks into controlling Starcraft or it would have probably been done by now. It would also be used for cheating so they can't make that anyway.
On the other hand. Pong is simple with 1 rule. Starcraft, or in this case Dota, have multiple facets to win.
Plus, most SC players just gg out of the game when they know they've lost. I'd think that is a more apt use for AI. Like chess, see out X moves; if it's a lost cause; call it, and get to the queue faster for another game.